1. Field of the Invention
The invention relates to a board placement method and system for a defective printed circuit board panel having multiple interconnected printed circuit board units, more particularly to an automated board placement method and system for a defective printed circuit board panel having multiple interconnected printed circuit board units.
2. Description of the Related Art
In the manufacture of a conventional printed circuit board panel, a plurality of independent printed circuit board units (hereinafter referred to as PCB units) are arranged and mounted on a substrate to form a printed circuit board panel having multiple interconnected PCB units so as to facilitate large-volume and quick component insertion on a production line. The defective product rate for printed circuit board panels having multiple interconnected PCB units during manufacture is about 5% to 7%. Since component insertion for a printed circuit board panel having multiple interconnected PCB units on a production line is generally set with fixed path values, whenever there is a defective PCB unit in the printed circuit board panel, most manufacturers will simply dispose of the same as non-usable, thereby resulting in waste of resources. Some manufacturers will identify the defective PCB unit in the printed circuit board panel in advance, and modify the component insertion path so as to skip the component insertion operation for the defective PCB unit. However, such a process is time-consuming and inefficient, and is not economically effective.
It is noted that the term “interconnected” as used herein means “structural interconnected,” not “electrically connected.”
In order to solve the aforesaid problems, generally, the defective PCB unit of the printed circuit board panel is cut out, and is replaced by a good PCB unit removed from another defective printed circuit board panel such that the printed circuit board panel becomes a good printed circuit board panel. Thus, defective printed circuit board panels having multiple interconnected PCB units can be utilized to avoid waste of resources. One such scheme is proposed in R.O.C. Invention Patent No. 228020.
In the aforesaid patent, optical positioning and computer positioning of the good PCB unit and the defective printed circuit board panel are performed by means of manual visual inspection of magnified images on a display, and the good PCB unit is simultaneously moved automatically or manually to be aligned with a vacant space in the defective printed circuit board panel. However, the aforesaid patent failed to disclose an automated process for performing moving alignment, which may be difficult in practice. After completion of the positioning is shown on the display, adhesive tapes are used to position the good PCB unit on the defective printed circuit board panel. Then, glue is injected manually to fill clearances between the good PCB unit and the defective printed circuit board panel, which are then delivered to a high-temperature furnace for curing. After the curing operation, manual steps are undertaken to remove the adhesive tapes, to inspect the circuit board panel, and to remove excess glue, thereby completing board replacement.
Furthermore, the aforesaid patent merely contemplates the positioning of the good PCB units on a planar surface. In practice, the surface of the printed circuit board panel is not a completely flat planar surface, and may have an inclination angle. Therefore, even if the good PCB unit is positioned according to the process disclosed in the aforesaid patent, if there is a drop between the good PCB unit and the printed circuit board panel at the joint, the printed circuit board panel will still be determined to be a defective printed circuit board panel.
In the board replacement process disclosed in the aforesaid patent and the conventional board replacement process adopted by manufacturers, with the exception of the cutting of the defective and good PCB units which is performed using a computer automated technique, the remaining operations are conducted manually. However, performing manual visual inspection concurrently with alignment and positioning is likely to affect precision. Besides, since the quality of the operators is inconsistent, unstable quality problems, such as a high redo rate, a low repair rate, etc., may result. In addition, the process of board replacement is complicated, and the speed of manual operation is slow, thereby resulting in low production capacity and rendering fast mass production impossible. Therefore, there is room for improving conventional techniques of board replacement for printed circuit board panels having multiple interconnected PCB units.